Dr. Allon has had a long-standing research interest in vascular access for dialysis, culminating in over 100 peer-reviewed publications during the past 15 years, as well as several funded NIH grants on this topic. His short-term goal is to improve our understanding of the clinical outcomes of patients receiving arteriovenous fistulas (AVF) and grafts (AVG). His long-term goal is to develop novel approaches to improve these clinical outcomes. Approximately 80% of U.S. ESRD patients initiate hemodialysis (HD) with a central vein catheter (CVC). Once HD has been started the patient is referred to a surgeon for creation of a permanent vascular access, either an AVF or an AVG. The current consensus guidelines strongly recommend placing an AVF, rather than an AVG. However, several small observational studies have suggested that AVG may be a better choice than an AVF in elderly HD patients, due to the higher AVF failure rate and relatively short patient survival. Primary access failure leads to prolonged CVC-dependence, with its attendant complications, until another functioning vascular access is placed and suitable for HD. We hypothesize that in older HD patients who initiate HD with a CVC, placement of an AVG rather than an AVF will result in shorter CVC-dependence, fewer episodes of CRB, fewer hospitalizations and longer patient survival. We propose a retrospective cohort study focused on new ESRD patients age >65 years who initiate HD with a CVC and no secondary vascular access (AVF or AVG), and who receive a subsequent AVF or AVG within 6 months of initiating HD. We will compare the 2 patient cohorts (AVF vs. AVG) in terms of primary access failure rate, duration of CVC-dependence after access placement, frequency of CRB, frequency of infection-related hospitalization and all cause hospitalization, and overall patient survival. The results of this observational study will b used to (1) provide valuable information about clinical outcomes in elderly HD patients receiving an AVF vs. an AVG after initiation of HD, and (2) provide robust information necessary to design and perform a power analysis for a definitive randomized clinical trial of AVF vs AVG in this study population.